CGX RA spike/PHD2 Log viewer

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KC_Astro_Mutt
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CGX RA spike/PHD2 Log viewer

#1

Post by KC_Astro_Mutt »

So last weekend, had a nice clear night. I've been chomping at the bit to use my new CGX with the AT130EDT. Everything worked great, I mostly was testing guiding and snapped a few test photos, with nice results. Guiding was actually pretty good, but I notice that the RA has twice (and up to 4 times) the RMS error as the DEC.



Like I said, guiding is good, but I wanted to investigate the RA swings. Changing the aggression setting didn't seem to change anything. I posted on the PHD2 group, and got a response from Bruce that my calibration steps were too short (don't know how to set them, as they are default to PHD2), and I had this spike at 34 seconds in my frequency analysis (whatever that is). He mentioned that I would have trouble getting good guiding at DEC 0. I know he's the expert, but if I'm reading it right, it appears the spike is only a .36 arc second error, not really much to worry about. Is this correct? I have the log viewer, but I don't really have a clue how to use it. Link to the log is below.

https://www.dropbox.com/sh/nefgbyyv3cym ... 9S3Ga?dl=0

Clear skies!
Jeff
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2022-05-13 17_48_58-PHD2 Log Viewer - PHD2_GuideLog_2022-05-06_195233.txt - PHD2 2.6.11 [Windows].png
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UlteriorModem
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Re: CGX RA spike/PHD2 Log viewer

#2

Post by UlteriorModem »

Jeff, might want to check the drive belt to see if it is not 'walking' out on the drive gear.

It was an issue with the CGX mounts when they were first released. The drive gear(s) were not parallel to the belt's drive path and causing the belt to work its way out towards the flange that holds it in place, then it would kind of snap back into place.



https://www.cloudynights.com/topic/7064 ... provement/
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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KC_Astro_Mutt
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Re: CGX RA spike/PHD2 Log viewer

#3

Post by KC_Astro_Mutt »

Thanks Tom! I did check on the belt first thing, however, no issue there. In the end, it's just not a problem, and is common to all CGX mounts.

Per Celestron Customer Support:
"The 34-sec spike you mention is common to all CGX mounts and the same thing happens to the CGX-L, but on a 21.4-second period as the worm gear turns every 5 minutes on the CGX-L instead of eight like on the CGX.
Traditionally, the spike is so small that it is not detected visually or photographically. You are actually the first person I have spoken with that has detected it by looking at PhD logs."

Jeff
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Re: CGX RA spike/PHD2 Log viewer

#4

Post by UlteriorModem »

Yea wow, I frankly have never noticed it either!
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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AstroBee
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Re: CGX RA spike/PHD2 Log viewer

#5

Post by AstroBee »

Check that belt tension too. It should be just tight enough to maintain position and not force the motor drive gear to be pulled towards the other fixed pulley. Not sure my terminology is correct at all but hopefully you get the idea. I was an early CGX adopter, in fact, on a waiting list for 6 months prior to its release. The first ones off the boat were over tensioned which caused the bearings to wear out prematurely. My guiding went from a regular of .40-.55" TRMS to over 2.0" over the course of about 3 months. I ended up having to ship it back to Celestron. To their credit, they did the repair and return shipping for nothing. But I was out a mount for 3 months.
Greg M.~ "Ad Astra per Aspera"
Scopes: Explore Scientific ED152CF & ED127 APO's, StellarVue SV70T, Classic Orange-Tube C-8, Lunt 80mm Ha single-stack solar scope.
Mounts: iOptron CEM70EC Mount, iOptron ZEQ25 Mount.
Cameras: ZWO ASI2600mm Pro, ZWO ASI1600mm
Filters: 36mm Chroma LRGB & 3nm Ha, OIII, SII Narrowbands
Eyepieces: 27mm TeleVue Panoptic, 4mm TeleVue Radian, Explore Scientific 82° 30mm, 6.7mm , Baader 13mm Hyperion, Explore Scientific 70° 10mm, 15mm, 20mm, Meade 8.8mm UWA
Software: N.I.N.A., SharpCapPro, PixInsight, PhotoShop CC, Phd2, Stellarium
https://www.alnitakproductions.com/Priv ... r-Project/
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